1. Field of the Invention
The invention relates to a double-acting high-pressure injector, which is intended for instance for injection fuel that is at high pressure into the combustion chambers of an internal combustion engine. In certain instances of use, in direct-injection internal combustion engines of large displacement, preinjection phases or postinjection phases may be necessary. The preinjection phase and the postinjection phase make stringent demands in terms of the precision of the triggerability of a control part that controls the injection phases in an injector housing, and in particular in terms of its production variations, if the intended injection courses are to be achieved.
2. Prior Art
German Patent DE 37 28 817 C2 relates to a fuel injection pump for internal combustion engines. In this disclosed fuel injection pump, the control valve member comprises a valve shaft, forming a guide sleeve and sliding in a conduit, and a valve head connected to the valve shaft and oriented toward the actuating device. The sealing face of the valve head cooperates with a face of the control bore that forms the valve seat. The valve shaft has a recess on its circumference, and the axial length of this recess extends from the orifice of the fuel supply line as far as the beginning of the valve head sealing face that cooperates with the valve seat. In the recess, a face exposed to the pressure of the fuel supply line is formed, which is equal in area to a face of the valve head that is exposed to the pressure of the fuel supply line, in the closed state of the control valve. As a result, in the closed state the valve is in pressure equilibrium, and a loading spring that urges the control valve member toward its open position is disposed in the guide sleeve on the control valve member.
With this configuration known from the prior art, it is not possible to achieve a preinjection phase, or a postinjection phase following the main injection phase, into the combustion chambers of an internal combustion engine, since to undertake an additional injection phase, there is no room available to receive the fuel volume to be injected during the preinjection phase or the postinjection phase.